CA1159603A - Composition for depositing metallic oxide film coatings - Google Patents

Abstract

A B S T R A C T

An organic solution of a composition consisting essentially of 100 parts by weight of an indium compound represented by the formula In(X)?(Y)m wherein X denotes a chelate ring formed by .beta.-diketones, esters of .beta.-keto-acids or the like, Y denotes an alkoxide formed by aliphatic alcohols or the like, and ? and m denote 1 or 2 having the relationship of ? + m = 3, and from 5 to 20 parts by weight of a tin compound represented by the formula Sn(X')2 or SN(Y')m' wherein X' denotes a chelate ring formed by .beta.-diketones or esters of .beta.-keto-acids, Y' denotes an alkoxide formed by aliphatic alcohols, and m' denotes 2 or 4, is suitable for deposition of transparent, hardened and low resistivity film coatings of tin-doped indium oxide on a substrate by means of the dip-coating method.

Description

l 1~9~03 S P E C I F I C A T I O N

COMPOSITION FOR DEPOSITING METALLIC OXIDE FILM COATINGS

The present invention relates to a composition for depositing metallic oxide film coatings, and more particularly, it relates to a composition suit-able for depositing tin-doped indium oxide film coatings of transparent, hardened and low electrical resistivity on a substrate by means of the dip-coating method.

Thin film coatings of indium oxide on substrates such as glass have being obtained by the vacuum deposition method, but the process often proves too costly for industrial applications. Spraying of solutions containing an indium compound on a heated substrate is recommended for the purpose, however, the process re-quires intricate apparatuses and techniques. In order to deposit thin film coatings of indium oxide on a substrate having a large surface area, the dip-coating method seems to be the most desirous process from industrial point of views. An organic solution containing such indium compounds as indium acetyl-acetonate and indium alkoxides may be suitable for the spraying method, however, indium alkoxides tend to hydrolyze during coating of the solution or during evaporation of the solvent in case of the dip-coating method is employed, and the hazy hydrolyzed compound coated on the substrate results deposition of opaque film coatings of indium oxide. As for indium acetoacetonate, though it does not hydrolyze during coating of the solution or during evaporation of the solvent, indium oxide film coatings obtained by the dip-coating method are not satisfac-torily transparent due to streaks on the coatings aypeared in the course of the baking.
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: , , l 1S9~03 It is, therefore, an object of this invention to provide a composition stuitable for depositing transparent film coatins mainly composed of indium oxide on an substrate by means of the dip-coating method.

It is another object of this invention to provide deposition of an indium oxide film coating which has low electrical resistivity.

The composition of the present invention comprises 100 parts by weight of an indium compound represented by the formula (I) ( )Q( )m (I) wherein X denotes achelate ring formed by ~-diketones, lower alkyl esters of ~-ketoacids, ~-hydroxyacids or alkanolamines, Y denotes an alkoxide formed by aliphatic alcohols, alkylene glycols or lower alkyl mono-ethers of alkylene glycols, and Q and m denote 1 or 2 having the relationship of Q + m = 3;
and from 5 to 20 parts by weight of a tin compound represented by the formula (II) Sn(X')2 or Sn(Y')m. (II) wherein X' denotesa chelate ring formed by ~-diketones or lower alkyl esters of ~-ketoacids, Y' denotes an alkoxide formed by aliphatic alcohols, and m' denotes 2 or 4, and the composition is suitable for deposition of transparent, hardened and low resistivity film coatings of tin-doped indium oxide on a substrate by means of the dip~coating met~od.
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Indium compounds reprensted by the formula (I) are characterized by possess-ing (X)Q and (Y) in the molecule, and preferable X and Y are as mentioned below;

X: a chelate ring formed by acetylacetone, methyl or ether ester of acetoacetic ~3 ' '~ " ~'' ' ' ' `

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1 ~59~3 acid, lactic acid and triethanolamine, and Y: an alkoxide formed by butyl alcohol, octyl alcohol, octylene glycol and mono~
methylether of ethylene glycol.

The indium compound possessing two chelaterings formed by methyl acetoace-toate and one n-butoxide may be prepared, for example, by reacting indium chloride (InCQ3) dissolved in an inert organic solvent such as n-hexane with two times mole of methyl acetoacetoate and an excessive amount of n-butyl alcohol in the presence of an acid-binding agent such as triethylamine. The obtained compound may be indicated by the following structural formula CH30 \ / CH3 HC~ / n~ CH

OBu The indium compounds are not necessarily to be pure compounds, but they may be mixtures of compounds represented by the formula (I).

For tin compounds represented by the formula (II) which possess X' or Y' in the molecule, preferable X' and Y' are as mentioned below;
X': a chelate ring formed by acetylacetone and methyl acetoacetoate, and Y': an alkoxide formed by butyl alcohol and octyl alcohol.

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The tin compounds are not necessarily to be pure compounds, but they may be mixtures of compounds represented by the formula (II).

~ or the purpose of the present invention, the compositions are used in a form of organic solution. In order to obtain a solution not hydrolyzed during coating of the solution or during evaporation of the organic solvent from the coated solution, the indium compound must be accompanied by the tin compound of the amount of from 5 to 20 parts by weight per 100 parts of the former.
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~ 15~3 Organic solvents employed for preparing organic solutions o the composition are not specifically limited, however, in consideration of easiness of evapora-tion of the solvent from the coated solution, aliphatic alcohols and esters of aliphatic acids having boiling points of below about 180C and their mixtures are usually employed. ~nd among them, aliphatic alcohols having less than 5 carbon atoms and acetic acid esters are preferably used.

Organic solutions containing the composition are prepared in ordininary con-ditions, and concentration of the component in the solution is usually settled at from 1 to 50 weight %.

Application of organic solutions onto a substrate is carried out by the dip-coating method inclucluding such methods as by dipping a substrate into solution and withdrawing at a predetermined rate, by immersing a substrate into the solu-tion and pumping out or withdrawing the solution, and by rotating a substrate and applying a desired amount of the solution to the substrate during rotation so as to make the centrifugal force spread the solution over the substrate.

The thickness of the resultant coatings may be controlled by varying concent-ration of the component in the solution, by varying the rate of withdrawal of the substrate from the solution, or by varying the speed of the rotation of a sub-strate.

The solution coated on a substrate is not affected by atmospheric moisture until the solution has been concentrated by evaporation oÉ the solvent from the coated solution at drying of the substrate. The drying is usually carried out at from 50 to 100C for from 10 minutes to 3 hours, and thin clear layer of the component is left on surface of the substrate. The component is stable until such time as the evaporation is completed, and this is one of the main distinc-tions of the present invention over known arts.

~ 5 -~ 159603 As explained above, since the composition is stable during drying o the solution coated on a substrate, the composition is especially suitable or ap-plying the solution onto a substrate by methods mentioned previously. It is to be understood that the solution is also applicable in such film-depositing methods employing the spraying and the airosol process, though they may include little chances of causing hydrolysis of the component by atmospheric moisture.

Substrates coated with thin layer of the component is baked in such ordinary conditions as at from 300 to 800C for from 10 minutes to 2 hours. Metallic oxides film coatings deposited on the substrate after baking are hard and trans-parent tin-doped indium oxide, and the coatings possess low electrical resistivity.
Accordingly, the film coatings obtained according to the present invention are useful in the fields of optics, electronics and solar energy.

Examples Solutions containing the component were prepared in accordance with prescrip-` tions mentioned in Table 1. An alkaliglass plate having the dimention of 70 X 30 X 1 mm were dipped in the solution, and the glass plate was withdrawn at a rate of 20cm/minute. The glass plate coated with the solution was dried at 60C for 30 minutes to vaporize the solvent. The dried coated glass plate was baked at 500C for 30 minutes. Thin film coatings deposited on the gIass plate were hard and transparent, and the thickness and sheet resistance are shown in Table 2.

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~, ~ 1 59~ 3 ~. Table __ Com- I (X)Q(Y)m Sn(X')2 or Sn(Y')m, Solution o~
posi- Compound Compound _ _ Compound Compound with with with with tion which which Q m Parts which which m' Parts Solvent Parts X is Y is by X' is Y' is by by No. formed formed wt. formed formed wt. wt.
_ _ _ _ ._ . . .. . _ .
1 AA n-BuOH 2 1 10 n-BuOH 4 1 EtAc 90

2 M i-OcOH 2 1 10 i-OcOH 4 1 EtAc 90

3 AA i-OcOH 1 2 10 n-BuO-H 4 1 EtAc 90

4 AA OcG 2 1 10 n-BuOH 4 1 EtOH 90 AA EGMeE 2 1 10 n-BuOH 4 1 EtOH g0 6 E M n-BuOH 2 1 10 n-BuOH 4 1 EtOH 90 7 MM n-BuOH 2 1 10 i-OcOH 4 1 EtOH 90 8 MM n-BuOH 1 2 10 n-BuOH 4 1 EtOH 90 9 MAA i-OcOH 2 1 10 n-BuOH 4 1 EtOH 90 LA n-BuOH 2 1 10 n-BuOH 4 1 MeOH 90 11 TEA n-BuOH 2 1 10 n-BuOH 4 1 EtOH 90 12 MAA n-BuOH 2 1 10 n-BuOH 2 1 EtAc 90 13 MAA n-BuOH 2 1 10 MAA 1 EtAc 90 14 MM n-BuOH 2 1 10 ¦ t-BuOH 4 1 EtAc 90 MM n-BuOH 2 1 10 ¦ t-BuOH 4 1.5 EtAc 90 16 MAA n-BuOH 2 1 10 t-BuOH 4 0.5 EtAc 90 17 MM n-BuOH 2 1 10 MAA 1 EtAc 40 18 MM n-BuOH 2 1 10 MAA . 1 CH2CQ2 40 19 AA n-BuOH 2 1 10 AA 1 CHCQ3 90 MAA i-OcOH 2 1 10 MAA 1 EtAc 90 21 MM n-BuOH 2 1 10 AA _ 2 EtAc 90 ___ Remarks) M: acetylacetone; EM : ethyl acetoacetoate; MAA: methyl aceto-acetoate; LA: lactic acid; TEA: triethanolamine; OcG: octylene glycol; EGMeE: mono-methylether of ethylene glycol B BuOH: butyl alcohol; OcOH: octyl alcohol; EtAc: ethyl acetate , . ' ' ' ,, .' ;

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~ 7 -~ ~598~3 Table 2 Composition No. Composition No.
Thickness Sheet . . Thickness Sheet with which wlth whlch film coating A Resistance film coating O Resistance w~s deposited ( ) (K ohm/~ ) was deposited ( ) (K ohm/~ ) . 300 35 14 400 8 7 400 7 18 1300 1.3 - :

300 40 l 21 300 20 ' :."' ~ . ~: . ,~ .

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Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS
CLAIMED ARE DEFINED AS FOLLOWS:

1. In a composition to be dissolved in an organic solvent and applied onto a substrate to deposit metallic oxide film coatings on the substrate, said composition consisting essentially of 100 parts by weight of an indium compound represented by the formula In(X)?(Y)m wherein X denotes a chelate ring formed by .beta.-diketones, lower alkyl esters of .beta.-ketoacids, .alpha.-hydroxacids or alkanolamines, Y denotes an alkoxide formed by aliphatic alcohols, alkylene glycols or lower alkyl mono-ethers of alkylene glycols, and ? and m denote 1 or 2 having the relationship of ? + m = 3;
and from 5 to 20 parts by weight of a tin compound represented by the formula Sn(X')2 or Sn(Y')m' wherein X' denotes a chelate ring formed by .beta.-diketones or lower alkyl esters of .beta.-ketoacids, Y' denotes an alkoxide formed by aliphatic alcohols, and m' denotes 2 or 4.

2. Composition according to claim 1, wherein X denotes a chelate ring formed by acetylacetone, methyl or ethyl ester of acetoacetic acid, lactic acid or triethanolamine, Y denotes an alkoxide formed by butyl alcohol, octyl alcohol, octylene glycol or mono-methylether of ethylene glycol, X' denotes a chlate ring formed by acetylacetone or methyl acetoacetoate, and Y' denotes an alkoxide formed by butyl alcohol or octyl alcohol.